Creo Options Modeler > References > Fundamentals > Creo Parametric User Interface > The File Menu > Opening Files > Previewing Assemblies
  
Previewing Assemblies
When you preview assemblies you can focus on individual assembly components. Click an assembly component in the preview area to get a preview of that component only.
For optimal assembly preview performance, set the save_model_display configuration option to shading_lod.